They sure do!

API: https://docs.mercury.com/docs/welcome

MCP: https://docs.mercury.com/docs/what-is-mercury-mcp

I run a small business books using mercury and beancount. The API supports enough operations in the free tier to do so with ease, though mostly I’m just fetching transactions. I do pay the ~35USD / mo for the extended API to get invoicing, though that’s not something a personal user would need

> I use ledger for plaintext accounting for both personal and business and sync of data is slightly annoying..

I made this to solve it https://sras.me/accounts/

Feel free to use it as it stores data on your browser's local storage only. For syncing between devices, you would be able to use Google firebase's free tier and export your accounts (after compressing and encrypting) there and import from another device. Let me know if you want to try it..